Various devices have been developed for measuring environmental conditions of a given location, such as temperature or pressure. However, numerous locations present challenges to many of these devices. For example, many devices may not be appropriate for use in higher temperature environments, such as geothermal wells, oil wells, or the like.
Certain conventional down-hole sensing techniques (e.g., for oil, gas, or geothermal applications) use distributed strain, temperature, and/or acoustic sensing. Pressure sensing along the length of a cable (or along the depth of a well or hole) may be performed using separately packaged sensors that are spliced along a length of a cable. For example, hydrostatic pressure may be transduced into longitudinal strain along an axis of the sensor, with the longitudinal strain used in determining pressure. However, the process of packaging and splicing sensors along a cable places practical limits on the numbers of pressure sensors along the length of the cable, and accordingly limits the numbers of locations for which pressure may be determined. The splicing of sensors into the cable and/or the use of transduced axial strain increases the cost, complexity, and/or instrumentation of distributed pressure sensing. Conventional approaches may also provide reduced resolution and/or present additional or alternative drawbacks. For example, certain conventional approaches may provide information for limited, discrete locations of a remote environment.
Temperature, strain, and/or acoustics may be measured along the length of an optical fiber by means of Raman, Brillouin, or Rayleigh scattering measurements, with distance resolution down to about one meter along the length of the cable possible. However, distributed pressure measurements (e.g., continuous or nearly continuous measurement of pressure along a length of a cable) may not be able to be made in the same manner.